Embedded flash video does not render/play in HTML export

First Symptom

Embedded flash video does not render/play in HTML export, with Error rendering macro 'multimedia' : null inside the html export

Steps to replicate

• Install a new confluence 5.5/5.9.4
• Create a new page
• Drag and drop a swf file to the page
• Save the page, and the video can be play from the page
  
• Export the page to html via Space tools

Expected Behavior
The video can be played just as inside the page

Actual Behavior
The video cannot be played directly, showing as an attachment with
Error rendering macro 'multimedia' : null error instead

Note

manually change the exported html file to include the segment below, it will play when the page is loaded:

<div class="innerCell">
<p><div class="embeddedObject" >
<object AllowScriptAccess="never" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="https://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,0,0" data="attachments\3997784\34373727.swf" height="1000" type="application/x-shockwave-flash" width="100%">
<embed AllowScriptAccess="never" play="true" autostart="true" height="1000" pluginspage="https://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash" quality="high" src="attachments\3997784\34373727.swf" type="application/x-shockwave-flash" width="100%">
</embed>
</object>
</div>
</p></div>